Recent studies in our laboratory have demonstrated that P. aeruginosa respond to soluble organic factors in spent culture medium that induce the disaggregation of biofilm cell clusters and result in a switch from a biofilm to a planktonic lifestyle. Preliminary results have demonstrated that these dispersed bacteria are significantly more susceptible to antibiotic treatment when compared to biofilm bacteria that have not been induced to disperse. We have extracted and purified the organic fraction from spent stationary phase cultures of P. aeruginosa (using glucose as a sole carbon source), and have tested this extract against biofilms formed by P. aerugjnosa, Klebsiella pneumoniae, Escherichia coli, Proteus mirabilis, Streptococcus pyogenes, Staphylococcus aureus, and Candida albicans. We have also tested this extract against mixed species biofilms with these organisms and have detected statistically significant dispersion in all cases when compared to control biofilms (p <0.05 in all samples assayed). Analysis of active HPLC fractions of the extracted organic material by NMR, IR and mass spectroscopy, has lead to the identification of a small messenger molecule which when synthesized in pure form and added to biofilms of P. aeruginosa, replicates the dispersion response detectable using the purified spent culture medium extract. We wish to test both the extracted organic dispersion inducer as well as the synthesized molecule to investigate the mechanism of the dispersion response in P. aeruginosa. Currently we have limited information regarding the role of protein synthesis or the release of lytic enzymes during the dispersion response. We are also limited in our understanding of the changes that occur with respect to phenotype and transcriptional regulation when biofilm bacteria transition to planktonic cells during the dispersion response. This proposal therefore, aims to investigate the role of the extracted organic dispersion inducer in inducing a change in the physiology of biofilm bacteria as they transition to a planktonic lifestyle. PUBLIC HEALTH RELEVANCE: The current application proposes work that will yield important information leading to an understanding of the biofilm dispersion response in P. aeruginosa. Findings from the proposed research are expected to lead to novel and improved strategies for the treatment of bacterial biofilms. The potential commercial possibilities for a compound that can induce dispersion in biofilms include enhanced treatment of biofilm infections, improved treatment of burns, improved removal of biofilm from surfaces, improved hygiene in hospitals, more effective cleaning products to improve health in the home, and others.